# How big a pool pump do I need?

**URL:** <https://boards.straightdope.com/t/how-big-a-pool-pump-do-i-need/496108>\
**Category:** Factual Questions\
**Created:** [May 11, 2009, 11:52pm UTC](https://boards.straightdope.com/t/how-big-a-pool-pump-do-i-need/496108 "2009-05-11T23:52:27Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![solkoe](https://avatars.discourse-cdn.com/v4/letter/s/919ad9/32.png) [@solkoe](https://boards.straightdope.com/u/solkoe)\
**Post date:** [May 11, 2009, 11:52pm UTC](https://boards.straightdope.com/t/how-big-a-pool-pump-do-i-need/496108/1 "2009-05-11T23:52:27Z")

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I have a 15’ x 25’ above ground pool that is 4’ deep. I run the pool water up about 8’ and through 2 solar heaters.  
What size pump would be necessary for this? Most above above ground pumps are 1 HP. Is this about right?  
Can anyone recommend a good economical brand? Which should I avoid?

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**Author:** ![Dag\_Otto](https://avatars.discourse-cdn.com/v4/letter/d/439d5e/32.png) [@Dag\_Otto](https://boards.straightdope.com/u/Dag_Otto)\
**Post date:** [May 12, 2009, 5:40am UTC](https://boards.straightdope.com/t/how-big-a-pool-pump-do-i-need/496108/2 "2009-05-12T05:40:09Z")

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That’s about 11,200 gallons. For a 6 hour turnover, you need a pump that can pump about 31 gallons per minute, at about (and I’m taking a guess here) 25 ft of head. (The 8’ needs to be considered, but I’d expect more loss though the filter). Have a pool guy help you determine the pressure drop though the filter.

Those are the numbers you need to find a pump - 31 gpm at 25 ft.

Turnover is based on the idea that you want all of the water in the pool to run through the filter every 6 hours. It won’t of course because of mixing, but it’s still a good way of sizing the pump.  
Judging from page 4 of [this cut sheet](http://www.bellgossett.com/BG-Literature-Detail.asp?LiteratureID=483&CatalogNum=36), a 1x1x5-1/4 with a 1/3 hp or 1/2 hp motor should do it.

Based on that 1 hp is too much. I don’t know what sort of pumps are available to you, but I’d guess 1/2 hp or less is what you need. But the numbers to start with are 31 gpm at 25 ft head.

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**Author:** ![Dag\_Otto](https://avatars.discourse-cdn.com/v4/letter/d/439d5e/32.png) [@Dag\_Otto](https://boards.straightdope.com/u/Dag_Otto)\
**Post date:** [May 12, 2009, 5:49am UTC](https://boards.straightdope.com/t/how-big-a-pool-pump-do-i-need/496108/3 "2009-05-12T05:49:02Z")

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> [@Dag\_Otto](#):
>
> a 1x1x5-1/4 with a 1/3 hp or 1/2 hp motor should do it.

Of course, that is for that manufacturer. Other manufacturers will have different (but similar) pump curves for their pumps.

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**Author:** ![solkoe](https://avatars.discourse-cdn.com/v4/letter/s/919ad9/32.png) [@solkoe](https://boards.straightdope.com/u/solkoe)\
**Post date:** [May 13, 2009, 12:57am UTC](https://boards.straightdope.com/t/how-big-a-pool-pump-do-i-need/496108/4 "2009-05-13T00:57:41Z")

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Thanks for the info.  
I’m going to have a hard time finding a 1/2 HP pump. Most above ground pool pumps are 1 HP. A small few are 3/4 HP. What options do I have?